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Intractable cancer pain, as well as chronic intractable benign pain, has been troublesome to the pain practitioner because of the short life span of conventional nerve blocks. Neurolytic agents have been in use since the turn of the 20th century for this particular group of pain patients for prolonged pain relief.

Neurolysis encompasses interruption of painful pathways by placement of a needle in the proximity of a nerve or plexus, either by injecting destructive chemicals or creating nerve obliteration by cold (cryotherapy) or heat energy (radiofrequency ablation).

This chapter focuses on the properties of the neurolytic agents and their clinical applications; separate chapters are dedicated to the other two techniques: cryotherapy and radiofrequency.

The first report of neurolysis was in 1863 by Luton, who injected subcutaneous irritant substances into painful areas and found that sciatic neuralgia was responsive to such therapy.1 Hartel reported the first use of caustic agents on nerve roots to interrupt pain fibers in 1914,2 and Doppler reported the use of phenol to destroy nerve tissues in 1926.3 Putnam and Hampton, in 1936, reported the first use of phenol as a neurolytic agent for gasserian ganglion block.4 In 1931, Dogliotti described the first use of alcohol for subarachnoid neurolysis to achieve prolonged relief.5 The first use of phenol for subarachnoid neurolysis was reported by Maher in 1955.6 Today, ethyl alcohol and phenol are the most widely used compounds; yet hypertonic saline, glycerol, ammonium salts, and chlorocresol have also been used.

Proper selection of patients for neurolytic blocks is the key to success of these potentially harmful procedures. After successful diagnostic local anesthetic blocks, a neurolytic block can be considered with reference to the cause and localization of the pain.7 If the patient is too debilitated, or the logistics of a procedure would not allow a trial local anesthetic block, diagnostic blocks can be combined with a neurolytic agent at the practitioner’s discretion. Clear communication of alternative techniques, outcomes, complications, expectations, and disease progression with the patient and the family is important prior to a neurolytic procedure.

A multidisciplinary approach, including an aggressive trial of opioids and adjuvant medications, along with temporary nerve blocks and psychological support are the mainstays of therapy.8 If these measures result in inadequate pain control or excessive nausea, sedation, or constipation, a neurolytic block should be strongly considered.

A thorough medical examination, including laboratory testing and imaging studies if appropriate, is necessary before performing a neurolytic block. Active infection, tumor involvement of the needle entry site, bleeding disorders, or concomitant anticoagulation therapy may be relative contraindications.

Currently, nerve stimulation techniques are widely used with all peripheral neurolytic blocks. Computed tomography (CT) or biplanar fluoroscopic guidance is common for neuroaxial and sympathetic neurolytic procedures. As in all invasive procedures, adherence to strict sterile technique is mandatory. Cardiovascular monitoring during and ...

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